1. Field of the Invention
The invention relates to an organic/inorganic hybrid material and the method for manufacturing the same, in particular to a metal alkoxide oligomer utilized in the organic/inorganic hybrid material, such that the material can be applied in high light extraction efficient LED sealing materials, thin and light myopia/hypropia lens, portable projector lens, high brightness LCD prism films, solar cell refractive photoelectric conversion mirrors, and camera phone/digital camera lens.
2. Description of the Related Art
Materials science is roughly divided into two major fields: organic materials and inorganic materials. The organic material such as polymer is easily moldable with better flexibility. The inorganic materials are better in mechanical strength, chemical resistance, and thermal stability. Recently, integrating organic and the inorganic materials have been a focus for those skilled in this art. The optical organic/inorganic hybrid materials are described below.
In development of high glass transition temperature (hereinafter Tg) and low moisture absorption polymethyl methacrylate (hereinafter PMMA) material, the properties of monomers in the copolymer are first considered. Although many types of monomers enhance the Tg and reduce moisture adsorption, three major factors should be evaluated simultaneously when choosing a type of monomer. The first factor is cost and availability of the monomers. Many monomers significantly improve the thermal properties of the product, however, they are expensive and hard to mass-produce, such that the mass production of the product cannot be ensured. This factor is the most important in choosing a type of monomer. Meanwhile, in certain conditions, some inexpensive monomers substantially improve product properties in low additive dosages, reducing product costs. Correspondingly, these monomers are the main focus of this invention. The second factor to evaluate when choosing a type of monomer is minimal property influence, such as transparency, birefringence, non-yellowing, moldability, and blue-light transparency. The last, and third factor is the monomers reaction to manufacturing and design influence, such as conditional reaction, reaction to corrosion resistance of the equipment, manipulation convenience, and innate nature of the monomer (e.g. toxicity, odor, or flammability).
In previous patents or research papers, monomers with hard and steric hindered side chain were introduced to copolymer with PMMA for enhancing the Tg of the PMMA copolymer. The monomers with hard and steric hindered side chain include tricyclodecyl methacrylic acid, tricyclodecyl acrylic acid, cyclohexyl methacrylic acid, n-octadecyl methacrylic acid, norbornyl methacrylic acid, and the likes. The method however, has a shortcoming of requiring a high additive dosage of the monomer with hindered side chain. For example, the additive dosage required is higher than 70 mol % to enhance the Tg above 120° C. of the PMMA copolymer. Because the monomers with hindered side chain are expensive, the high additive dosage decreases the economic value. Additionally, PMMA contain carbonyl group which has strong dipole interactions. If other monomers in the PMMA copolymer cannot provide sufficient molecular interaction, the Tg of the PMMA copolymer will be seriously reduced. Accordingly, previous research has so far failed to improve the Tg of the PMMA copolymer by introducing inexpensive monomers.
In development of organic/inorganic hybrid materials, the high refractive index materials are made by two principal methods. The metal oxide is introduced into polymer matrix by physical blending or chemical sol-gel process. Physical blending limits the content ratio of inorganic powder in the polymer matrix, such that the refractive index and the transparency of the material can not be efficiently improved.
Chemical sol-gel process, dissolves the organic polymer and inorganic salt such as metal alkoxide, non-metal alkoxide, or other inorganic salt in an acidic solution. The inorganic salt is then hydrolyzed and reacted with the organic polymer to form a sol-gel material.
As disclosed in Japan Patent Publication No. 2002-516249-W and 200344504-A, TiO2 was introduced into the polymer by a sol-gel process. The sol-gel process includes dissolving inorganic precursor, organic monomer, and surface modifier in solvent, processing hydrolyzation/condensation to form powder, and polymerizing the powder to form a product. The product has a refractive index of greater than 1.5.
As disclosed in U.S. Pat. No. 6,103,584, the organic/inorganic hybrid polymer is obtained by the process in which a polymer having a polycarbonate and/or a polyarylate moiety as a main frame and having a metal alkoxide group as a functional group, is hydrolyzed and polycondensed to form crosslinkages. The alkoxide can be oligomer type such as alkoxysilane oligomer.
As disclosed in U.S. Pat. No. 6,228,796 and 6,068,690, an organic-inorganic hybrid polymer material in which an organic polymer component and a metal oxide component are covalently bonded with each other, which is obtained by hydrolyzing and polycondensing a solution or a wet gel which comprises an organic polymer having an alkoxymetal group as a functional group or an organic polymer having a functional group reactable with a metal alkoxide compound, and a metal alkoxide compound. Although in Example 6 of '796 the titanium alkoxide oligomer is utilized as a photo-catalysis layer, the organic polymer still basically serves as a backbone.
Metal alkoxide oligomer is applied in varied fields. For example, Chiba disclosed a magnetic coating material applied in tape or disk in U.S. Pat. No. 5,429,899. The magnetic material includes titanium alkoxide oligomer as the following formula:
Linear type such as those having the following formula:
wherein n is 2-40.
Ladder type such as those having the following formula:
wherein n is 1-40.
Highly condensed type such as those having the following formula:
wherein n is 2-40.
In the above formula, X represents independently hydroxyl group, ether group, halogen, or other functional groups.
The described titanium alkoxide oligomer is only mixed with organic molecules to become a magnetic coating material; however, the titanium alkoxide oligomer is not integrated into polymer backbone.
Another application of metal alkoxide oligomer is disclosed in U.S. Pat. No. 6,068,690. Aizawa et al. mix the titanium alkoxide oligomer solution and the zirconium alkoxide oligomer solution to form Ti—O—Zr precursor. The Ti—O—Zr precursor is further reacted with lead alkoxide oligomer to form Pb(Ti—O—Zr) alkoxide applied in ferroelectric film. Although several titanium alkoxide oligomers are applied in this patent, they are not applied in organic/inorganic hybrid materials.